The present invention relates to a sealing assembly of the two-lip type which can be interposed between two relatively movable members to make a seal between them, preferably, but not exclusively, able to be interposed between the outer and inner rings of a rolling element bearing.
It is known that numerous types of sealing assemblies of the two-lip type exist, which can be interposed between the rings of a rolling element bearing for the purpose of isolating the cavity between the rings themselves and containing the rolling elements, from the surrounding environment in such a way as to prevent the escape of lubricant or the ingress of contaminating agents such as water or dust into the cavity itself.
A first type of known sealing assembly comprises a metal ring of suitable shape which can be force fitted to the outer ring of the bearing and a second ring of elastomeric material provided with two radial lips operable to slide with a predetermined pressure on the outer surface of the inner ring of the bearing in such a way as to exert on it a sliding seal both against external agents which tend to enter into the said cavity, and against lubricant which tends to escape from this.
A second type of sealing assembly comprises two metal rings force-fitted between the bearing rings and a ring of elastomeric material fixed to one of the metal rings and having two lips, one radial and the other axial, which can exert an associated sliding seal on the other metal ring.
The above described sealing assemblies have various disadvantages. In particular, these sealing assemblies are bulky, which is especially unacceptable in applications relating to rolling element bearings. Moreover, if these assemblies are not provided with spring pressure elements the seal can become ineffective with time; on the other hand if spring elements are present these increase the bulkiness especially in the case in which a double seal, both radial and axial is desired, and consequently reduces the space for the lubricant grease and/or renders impossible the provision between the sealing lips of a collection space of sufficient dimensions for this grease, with consequent low durability and efficiency of the seal.